Pursuant to Section 13 or 15(d) of the Securities
Exchange Act of 1934

Date
of Report (Date of earliest event reported): November 29, 2012

Plug Power Inc.

(Exact name of registrant as specified in its charter)

Delaware

1-34392

22-3672377

(State or other jurisdiction

(Commission File

(IRS Employer

of incorporation)

Number)

Identification No.)

968
Albany Shaker Road,
Latham, New York

12110

(Address of principal executive offices)

(Zip Code)

Registrant’s
telephone number, including area code: (518) 782-7700

N/A

(Former name or former address, if changed since
last report.)

Check the appropriate box
below if the Form 8-K filing is intended to simultaneously satisfy the filing
obligation of the registrant under any of the following provisions (see General
Instruction A.2. below):

On November 29, 2012 Plug Power Inc. (the “Company”) executed
a Third Loan Modification Agreement (the “Loan Modification”) with
Silicon Valley Bank, amending the August 9, 2011 Loan and Security Agreement (as
modified by the First Loan Modification Agreement, dated as of September 28,
2011 and the Second Loan Modification Agreement, dated as of March 30, 2012,
both by and between the Company and Silicon Valley Bank, the “Loan
Agreement”). The Loan Modification, among other things, waived the
Company’s failure to comply with the Adjusted Quick Ratio financial
covenant as of the months ended September 30, 2012 and October 31, 2012, revised
the future Adjusted Quick Ratio covenant level and removed the Company’s
ability to request financing for Inventory Placeholder Invoices. A copy
of the Loan Modification is attached hereto as Exhibit 10.1 and is incorporated
herein by reference. The remaining terms of the Loan Agreement, as
disclosed in the Company’s Quarterly Report on 10Q filed on November 14,
2012, remain in full force and effect.

Item 9.01.
Financial Statements and Exhibits

(d)
Exhibits.

10.1 Third
Loan Modification Agreement dated November 29, 2012, by and between Plug Power
Inc. and Silicon Valley Bank.

2

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act
of 1934, the registrant has duly caused this report to be signed on its behalf
by the undersigned hereunto duly authorized.